Custom mandel bent exhaust

[Nathan]

So my engine is here: http://www.cardomain.com/id/fstrnu240 and I am very happy! BUT, I now need to put some more thought into the exhaust system. The engine should be pushing about 300 hp and hence I will be needing a good free flowing exhaust system, I would go with a pre-made one such as the Apexi N1 but for one thing I hate shiny things, for another...I think I could have a custom 3 in. mandel bent system welded up cheaper. I also want the system to be very quiet so I was thinking of this: 3 in. mandrel bent tubing, a good high flowing catalyic converter (random technologies, etc. anyone have an affordable recommendation?) I was thinking of using a 3 in. inlet/outlet glasspack muffler as a resonator followed by a magnaflow muffler since it is a straight through design but large and looks to me like it would muffle the sound better than some other straight through designs. I'm also planning on setting the muffler a little back from the bumper and just having a crappy looking 3 in. section of exhaust tubing running out to the back of the bumper for that crappy exhaust system look (very important to me) How quiet do you guys think that this system would be compared to other exhausts such as the Apexi N1...I dont want it to sound ricey at ALL, it has to be as deep as possible without having any sharp raspy noises. Does anyone have any cheaper alternatives to the parts I listed? Random Tech. cats are pricey as heck and dynomax has come out with a cheaper high flow cat...does anyone know how good it is? I could not find much info or cat comparisons online. Does anyone know of a cheaper straight through muffler that is not a canister design, or if it is...that isnt highly polished? Finally, who thinks I should just make up a test pipe out of leftover exhaust tubing and say screw it to the cat? thanks for the input! Oh, and in case you didnt check my link and see whats going on, its a CA18DET engine with a HKS GT2540 turbo, apexi power fc, 720cc injectors...all the goodies to need a good free flowing exhaust system.

[zachosz]

If you want a quiet exhaust you should have a cat as they kinda act like mufflers too. I guess any one you get will perform the same as long as it's a high flow unit, a glass pack sounds ok but they tend to get louder with age, for muffler i would get a Dynomax or Flowmaster, they sound great, no experience on Magnaflow.

[Nathan]

Actually, I intended to use both the glass pack and a muffler...the glass pack would be a resonator to cut down the sound and remove some raspiness and then the muffler would seal the deal. I know the cat works as a muffler too to a degree but its so friggin expensive for a good one, and it seems that they actually are NOT all created equal. Catco Hi-Flow cats dont flow much better than a norma cat for instance (I dont remember where I ran across that info so dont ask me to back it up ) Also, flowmaster does not make a straight through muffler do they? I need a minimal amount of backpressure and a straight through muffler is a necessity. Dynomax does make some straight through mufflers and is another brand I am considering despite the fact that their straight through mufflers are canister style by design and I think the Magnaflow would be better at muffling the sound. Thank you for your input!

[slw240sx]

ahh Nathan , the exhaust with a gutted cat and muffler isnt that loud reallly

[Nathan]

Hehe, I'm just psycho about nobody knowing what's under the hood (including any police officers I drive by...the less reasons to pull me over the better) And I like the sleeper aspect of a nice quiet exhaust...What kind of muffler are you talking about Jon? I might end up just gutting a cat if I can find a 3in inlet/outlet...but I'll eventually have to get a cat to pass inspections (I THINK I can pass the sniffer if I keep the boost really low and lean out the a/f mixtures at lower rpms).

[sil80drifter]

Well my muffler fell off, my cat is stock, and my car is louder than all hell when i rev it from 750 to 6500. at 3k steady cruise it's kinda loud inside too. I have to turn the stereo up to 90% (and it's a good stereo). then again, I'm NA, and ur running a turbo, which accounts for about 1/3 of muffling in a turbo system. so maybe u'll be pretty damn quiet with a gutted cat and a muffler.

sil80

[Nathan]

Just to re-state in a shorter post...I'm thinking of a 3 inch downpipe going to a random tech cat or a gutted cat (or any other high flow cat people can think of...suggestions are welcome!) this will go to a glasspack which will be a resonator just to muffle the exhaust a bit followed by a length of 3 inch exhaust pipe going to a nicer good muffler to finish things off. Yeah, I'm hoping the turbo quietens it down a bit sil80 that sucks that your muffler fell of! My friend unbolted his exhaust from the exhaust manifolds back on his explorer and it was dang loud too.

[sil80drifter]

oh oh! look!

http://home.earthlink.net/~tmahon281/image.html

not our car, but u get the idea. gus was the man. RIP.

heving read this one, i would go with the ultraflow, personally.

sil80

[Nathan]

ahhh, thanks for digging that up sil80, I'd read it before but had forgotten...ok, now I just need to figure out who carries an ultraflow muffler Talking with GoofyATX I came up with another idea for the cat issue too...make a test pipe out of the spare exhaust tubing and weld some flanges onto it...then take the crappy stock cat that is on the car now (providing it is still any good, anyone know how to tell?) cut the flanges off of the cat and get a reducer that goes from 3 inches down to whatever the inlet/outlet diameter is on the stock cat...then weld on the reducers on either side and weld flanges to the reducers...presto I can use the old crappy cat when I go in for emissions testing it'll be super cheap and even if it doesnt work I can just go buy a decent cat!

[sil80drifter]

sounds like a good idea for emissions...my lord i hate those...blah!

sil80

[Nathan]

bump...anyone else have any input on this? If I posted a thread saying: Apexi or HKS exhaust? everyone would JUMP on it...grrr

[Nathan]

Has NOBODY else tried making their own exhaust? come on there are like 4 or 5 boring threads that have more hits than this one...its a reasonably important thing, some people might be looking to make their own exhaust and want ideas! Lets hear some more input

[erich]

Has NOBODY else tried making their own exhaust? come on there are like 4 or 5 boring threads that have more hits than this one...its a reasonably important thing, some people might be looking to make their own exhaust and want ideas! Lets hear some more input

I made my own exhaust. 2.5 inch stainless from the turbo back. The only thing not stainless is the Thrust glasspack to knock the noise down a bit. There aren;t any good pictures of the exhaust on my website but I might be able to dig a couple up.http://www3.telus.net/kreen

[Nathan]

Ahhhh, see I knew I couldnt be the only enterprising person around here! How loud is your exhaust, especially in comparison to other aftermarket systems? Thanks for the response erich, nice car!

[erich]

Oddly enough the car is louder on the inside then the outside. I think that is mainly due to the fact that I haven't put any tips on the muffler (a cheap vibrant 2.5 in, dual 2 out) and the tips are behind the plane of the bumper plastic a bit. The glasspack really helped out. It is a Thrush 28 inch long by 2.5 inch diameter. It is quiet enough that I don't seem to ever attract attention which is exactly what I wanted.

Here is apicture of the exhaust before I put in the Thrush glasspack. It had a Vibrand glasspack that didn;t do anything noticable so I changed it.

http://www3.telus.net/kreen/exhaust.jpg

[sixxdeuce]

Flowmasters are supposed to have better flow than straight through mufflers. The way the chambers are designed causes a vacuum effect and is more effictive at scavenging exhaust gasses. Alot of people dont even consider flowmasters because they are mainly for domestic muscle cars, but this narrowminded thinking causes them to miss out on a good product. If you want quiet then get one with delta flow technology, mellow but nice and deep.

[MR2NER]

I hear so much talk about how a well built custom mendrel bend system is just as get as a brand name catback. Does anyone have dyno sheets to prove this. I'm not doubting anyone, I'm just curious as to what type of gains they have gotten from such a system. I'm writing this because I'm very tempted to just buy some universal muffler and get a custom system for cheaper than an apexi,hks, or tanabe catback.

[Nathan]

Thanks for the input guys...Erich, that was the kind of information I was looking for...I'm trying not to be noticed as well Sixxduece, I will look further into the prospect of a Flowmaster and perhaps reconsider. Mr2ner, in theory if you can have the same flow level at the same velocity as a premade system then horsepower will be the same. I believe a well designed home made design can be as good as a tanabe, apexi, hks etc...I think that you will at least not notice a difference between them.

[erich]

I hear so much talk about how a well built custom mendrel bend system is just as get as a brand name catback. Does anyone have dyno sheets to prove this. I'm not doubting anyone, I'm just curious as to what type of gains they have gotten from such a system. I'm writing this because I'm very tempted to just buy some universal muffler and get a custom system for cheaper than an apexi,hks, or tanabe catback.

A friend has a flowbastard on his 93 G20. 15 months after the install it started rusting through. They are loud and droney. He is gonig to switch to ANYTHING else this summer when the turbo goes in.